To create a construction estimate in Excel, start by setting up a table with columns for project details like client name, project description, and date, then add separate sections for different cost categories like materials, labor, equipment, subcontractors, overhead, and profit; within each category, list individual items with their quantity, unit cost, and calculated total cost, using formulas to automatically sum up each section and generate a grand total; remember to format the cells appropriately with currency symbols and consider creating a template for consistent use.